Light-scanning microscope with simplified optical system, more particularly with variable pupil position

Abstract

A light-scanning microscope including a scan optics for generating a pupil plane conjugate to the pupil plane of the microscope objective, and a variably adjustable beam deflection unit in the conjugate pupil plane. An intermediate image lies between the microscope objective and the scan optics. The scan optics image a second intermediate image (Zb2) into the first intermediate image via the beam deflection unit, wherein the second intermediate image is spatially curved. The deflection unit is not arranged in a collimated section of the beam path, but is instead arranged in a convergent section. Then, in terms of the optical properties and quality thereof, the scan optics needs rather to correspond merely to an eyepiece instead of a conventional scanner objective.

Description

[0001]The present application claims priority from International Patent Application No. PCT / EP2015 / 058328 filed on Apr. 16, 2015, which claims priority from German Patent Application No. 10 2014 005 880.8 filed on Apr. 17, 2014, the disclosures of which are incorporated herein by reference in their entirety.FIELD OF THE INVENTION[0002]It is noted that citation or identification of any document in this application is not an admission that such document is available as prior art to the present invention.[0003]The invention relates to a light-scanning microscope comprising an optical system, which defines an illumination beam path and comprises the following components: a light source, which provides a spatially restricted light distribution, a microscope objective comprising a (light-source-side) pupil plane and an (objective-side) focus, a scan optics (also referred to as “scan lens”) for generating a pupil plane conjugate to the pupil plane of the microscope objective, and (in respe...

AI Technical Summary

Benefits of technology

[0011]The invention is based on the object of improving a microscope of the type set forth at the outset such that the scan optics can have a simpler design and it is possible to provide more installation space for the deflection unit.

[0018]Expediently, the optical system may comprise a collimation optics (in the illumination beam path or in the detection beam path) on a side of the beam deflection unit distant from the scan optics. In this manner, further manipulations on the beams and the final detection are possible with little outlay.

[0019]Preferably, (exactly) one concave mirror, the center of curvature of which lies in the conjugate pupil plane, lies optically between the beam deflection unit and the light source or the transducer, in particular as a collimation optics. The concave mirror has an achromatic effect. In this manner, a further conjugate pupil plane can be provided with little optical outlay, in particular with a small number of interfaces. By arranging the concave mirror at the distance of the radius of curvature thereof from the first conjugate pupil, it is possible to provide (via a curved second intermediate image) a highly precise image at the same distance, independently of the field angle.

[0022]Preferably, the concave mirror, in particular the reflecting surface thereof, has a toric form (surface form of a toroidal section), with the invention also comprising other forms. As a result, the astigmatism resulting from oblique incidence can be reduced. Here, the concave mirror preferably has a first radius of curvature, which is smaller than twice the radius of curvature of the intermediate image by a factor cos (angle of incidence), and a second radius of curvature, which is greater than twice the radius of curvature of the intermediate image by a factor cos(angle of incidence). Preferably, the first curvature belonging to the first radius of curvature extends about an axis which is parallel to an axis of rotation of the first beam deflection unit and the curvature belonging to the second radius of curvature is orthogonal to the first curvature.

[0031]Embodiments in which the microscope objective is arranged in a manner displaceable along the optical axis and / or in an objective changer, in particular comprising an electric drive for displacing the microscope objective and / or for interchanging the microscope objective, are advantageous. As a result, great flexibility when measuring with an unchanging high imaging quality is rendered possible in conjunction with the adaptability to the different pupil positions of different objectives.

[0032]Preferably, the first beam deflection unit and / or the second beam deflection unit have / has a micro-electromechanical system for setting the beam deflection. Like in U.S. Pat. No. 7,295,726 B1, this may provide rotatability about two different axes, in particular with the position of the (stationary) point of intersection of these axes in a reflecting surface (deflecting the beam coming from the scan optics), in particular with the arrangement of this point of intersection on the optical axis of the detection beam path. MEMS-based scanners have a significantly lower mirror mass and, as a result thereof, have the advantage of being able to be tilted quickly in any way and with high accuracy. By way of example, one of the beam deflection units may be a MEMS-based mirror which is only adjustable about exactly one axis of rotation and the other beam deflection unit may be a galvanometric scanner. Here, the galvanometric scanner may also be operated resonantly.

Problems solved by technology

Here, the quadratic dependence (in the case of the two-photon excitation) or cubic dependence (in the case of the excitation of the third harmonic or the three-photon excitation) of the light emission in the sample on the intensity in the case of the conventional arrangement of a plurality of beam deflection units in a respective pupil in such a way that the deflection units are not imaged on one another leads to problems in the image field illumination.

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